The isolation of a lactone compound C15H18O8 from the leaves of Ginkgo biloba, to which the name bilobalide was given, was first mentioned in 1967 by R. T. Major (Science 157 (1967), p. 1270-1273). The structural formula for said bilobalide was already proposed in 1971 (J. Amer. Chem. Soc. 93 (1971), p. 3544-3546) and is as follows:

The active main components of Ginkgo are alkylated phenoles such as ginkgol and 3-(8-pentadecenyl) phenol, and phenolic carboxylic acids such as 2-hydroxy-6-(8-pentadecenyl) benzoic acid, ginkolide and bilobalide. Bilobalide, a sesquiterpene, and ginkgolide, a hexacyclic diterpene, are the only known naturally occurring compounds having tert. butyl groups. Said substances may be isolated from the leaves and other organs of the Ginkgo biloba tree, e.g. bilobalide is found in the leaves of Ginkgo biloba at concentrations below 0.01%.
The known extracts have been used for the treatment of disturbances of cerebral and peripheral arterial blood flow. The contained ginkgo-flavone glycosides and terpenoids are known to have vaso-regulating and blood viscosity decreasing properties. The main indications for which Ginkgo is prescribed in Western countries, such as France and Germany, is cerebral insufficiency. Further, Ginkgo biloba has been extensively used for various indications in Chinese medicine and is described in the traditional Chinese Pharmacy.
In recent years also complexes between natural or synthetic phospholipids and bilobalide, as well as preparations thereof, have been investigated. The U.S. Pat. No. 5,043,323, for example, discloses complex compounds of bioflavonoids with phospholipids, including Ginkgo biloba complexed with phosphatidyl serine.
Furthermore, the U.S. Pat. No. 5,202,313 suggests their therapeutic application as antiinflammatory agents and as agents for the treatment of disorders associated with inflammatory or traumatic neuritic processes.
Moreover Ginkgo extracts are known to have effects on cognitive functions. For example V. D. Petkov et al., Planta Med. 59 (1993), pp. 106-114, disclose that the standardized extracts of Panax ginseng, Ginkgo biloba and a combination thereof improve the learned behavior of young and old rodents.
According to the teaching of WO 01/43753 A2 it was found in cognitive tests that administering a combination of extracts of the root of Panax ginseng and of the leaves of Ginkgo biloba to humans positively effects cognitive skills, for example the speed and quality of memory in normal healthy subjects.
Furthermore, there has been a variety of studies on the influence of ginkgo biloba extract on cognitive performance. It has been suggested (Moss and Scholey 1996, Scholey et al 1999, Kennedy and Scholey 2000) that some demanding cognitive tasks may be facilitated by the simple augmentation of delivery of metabolic substrates to the brain. As an example, a previous study from this laboratory (Kennedy and Scholey 2000) investigated the relationship between heart rate, blood glucose levels and performance on a “demanding” mental arithmetic task (serial verbal subtraction of 7 from a given number between 800 and 1000), a “less demanding” mental arithmetic task (serial subtraction of 3), and a long term verbal memory task. It was found that not only both serial subtraction tasks engendered significant increases in heart rate above that engendered by somatically identical counting tasks, but that performance on both was also related to the magnitude of fall in blood glucose levels during task performance. Performance on the most demanding task (serial 7s) was also not only improved by a glucose drink, but was also related to resting heart rate.
However the effects according to the use of the inventive complex are superior and of a novel type.